bitmap: Fix some bugs on 32-bit platforms

The bitmap_word type is an unsigned long. However in some places we assign it using -1ULL, a 64-bit value on many platforms. We sometimes get away with this because it masks correctly, but in other cases it breaks things. To clean this up define a new BITMAP_WORD_1 constant, indicating a bitmap_word with all bits set, and use that instead of explicit UL or ULL qualifiers. Signed-off-by: David Gibson <[email protected]>
xzou999 · Jul 11, 2019 · cdd0b8b · cdd0b8b
1 parent ce4660a
commit cdd0b8b
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Showing 2 changed files with 10 additions and 7 deletions.
diff --git a/ccan/bitmap/bitmap.c b/ccan/bitmap/bitmap.c
@@ -13,8 +13,8 @@ void bitmap_zero_range(bitmap *bitmap, unsigned long n, unsigned long m)
 {
 	unsigned long an = BIT_ALIGN_UP(n);
 	unsigned long am = BIT_ALIGN_DOWN(m);
-	bitmap_word headmask = -1ULL >> (n % BITMAP_WORD_BITS);
-	bitmap_word tailmask = ~(-1ULL >> (m % BITMAP_WORD_BITS));
+	bitmap_word headmask = BITMAP_WORD_1 >> (n % BITMAP_WORD_BITS);
+	bitmap_word tailmask = ~(BITMAP_WORD_1 >> (m % BITMAP_WORD_BITS));
 
 	assert(m >= n);
 
@@ -38,8 +38,8 @@ void bitmap_fill_range(bitmap *bitmap, unsigned long n, unsigned long m)
 {
 	unsigned long an = BIT_ALIGN_UP(n);
 	unsigned long am = BIT_ALIGN_DOWN(m);
-	bitmap_word headmask = -1ULL >> (n % BITMAP_WORD_BITS);
-	bitmap_word tailmask = ~(-1ULL >> (m % BITMAP_WORD_BITS));
+	bitmap_word headmask = BITMAP_WORD_1 >> (n % BITMAP_WORD_BITS);
+	bitmap_word tailmask = ~(BITMAP_WORD_1 >> (m % BITMAP_WORD_BITS));
 
 	assert(m >= n);
 
@@ -65,7 +65,7 @@ static int bitmap_clz(bitmap_word w)
 	return __builtin_clzl(w);
 #else
 	int lz = 0;
-	bitmap_word mask = 1UL << (BITMAP_WORD_BITS - 1);
+	bitmap_word mask = (bitmap_word)1 << (BITMAP_WORD_BITS - 1);
 
 	while (!(w & mask)) {
 		lz++;
@@ -81,8 +81,8 @@ unsigned long bitmap_ffs(const bitmap *bitmap,
 {
 	unsigned long an = BIT_ALIGN_UP(n);
 	unsigned long am = BIT_ALIGN_DOWN(m);
-	bitmap_word headmask = -1ULL >> (n % BITMAP_WORD_BITS);
-	bitmap_word tailmask = ~(-1ULL >> (m % BITMAP_WORD_BITS));
+	bitmap_word headmask = BITMAP_WORD_1 >> (n % BITMAP_WORD_BITS);
+	bitmap_word tailmask = ~(BITMAP_WORD_1 >> (m % BITMAP_WORD_BITS));
 
 	assert(m >= n);
 

diff --git a/ccan/bitmap/bitmap.h b/ccan/bitmap/bitmap.h
@@ -15,6 +15,9 @@ typedef unsigned long bitmap_word;
 #define BITMAP_NWORDS(_n)	\
 	(((_n) + BITMAP_WORD_BITS - 1) / BITMAP_WORD_BITS)
 
+#define BITMAP_WORD_0		(0)
+#define BITMAP_WORD_1		((bitmap_word)-1UL)
+
 /*
  * We wrap each word in a structure for type checking.
  */